V4L control units

Moikka
What is preferred way implement controls that could have some known unit or unknown unit? For example for gain controls, I would like to offer gain in unit of dB (decibel) and also some unknown driver specific unit. Should I two controls, one for each unit?

Like that

V4L2_CID_RF_TUNER_LNA_GAIN_AUTO
V4L2_CID_RF_TUNER_LNA_GAIN
V4L2_CID_RF_TUNER_LNA_GAIN_dB

regards
Antti

http://palosaari.fi/